Mongodb – Upgrade mongodb from 2.4 to 3.0

mongodb

I have mongodb 2.4 database with some indexing. Now I want to upgrade that version to 3.0. I searched on google but did not find any firm answer. I tried installing 3.0 but then it gives me error of index.
Does anybody have idea about this?

Answer:

I am able to upgrade the DB. Below are the steps :
1. Install mongodb 2.6
2. Update the index of admin collection
db.getSiblingDB("admin").runCommand({authSchemaUpgrade: 1 });
3. Install mongodb 3.0

Best Answer

Upgrade Requirements To upgrade an existing MongoDB deployment to 3.0, you must be running 2.6. If you’re running a version of MongoDB before 2.6, you must upgrade to 2.6 before upgrading to 3.0. See Upgrade MongoDB to 2.6 for the procedure to upgrade from 2.4 to 2.6. Once upgraded to MongoDB 2.6, you cannot downgrade to any version earlier than MongoDB 2.4.

http://docs.mongodb.org/manual/release-notes/2.6-upgrade/

One of the most important thing to remember after you are on 2.6 if you are trying to use WiredTiger as your storage engine, you do need to take a mongodump by connecting into current mongodb version and then switch to mongodb 3.0 with a different db path,

IMP: You will not be able to use existing DB path as previous storage on mmapv1

Command to use: mongod --storageEngine wiredTiger --dbpath

mongodump and mongorestore can operate against a running mongod process, and used to take a backup and restore the backup respectively.

http://docs.mongodb.org/manual/reference/configuration-options/

storage.engine
Default: mmapv1

New in version 3.0.0.

Specifies the storage engine for the mongod database. 
Valid options include mmapv1 and wiredTiger.

If you attempt to start a mongod with a storage.dbPath 
that contains data files produced by a storage engine other 
than the one specified by storage.engine, 
mongod will refuse to start.

Related Solutions

MongoDB WiredTiger on Ubuntu – Installation and Configuration

I wasn't able to use wiredTiger upgrading MongoDB. However, at May 17 I uninstalled MongoDB 2.6 then installed MongoDB 3.0.3 . Immediate after the installation, I added storageEngine=wiredTiger on top of my mongod.conf file. Then I gave sudo service mongod start command and eventually I could.

Edit:

For fresh installed as directed by official documentation;

Open configuration file using sudo nano /etc/mongod.conf
Change the # engine line to engine: wiredTiger like the below
Run mongod using the command sudo service mongod start

# Where and how to store data.
storage:
  dbPath: /var/lib/mongodb
  journal:
    enabled: true
  engine: wiredTiger
#  mmapv1:
#  wiredTiger:

Edit:

If the current version is supported the wiredTiger;

Get the backup of the current database using mongodump command
Stop the mongod service using sudo service mongod stop command
Add storageEngine=wiredTiger text as the first line of mongod.conf file
Delete the all file on /var/lib/mongodb (or /data/db folder if used)
[This is important. Because MongoDB cannot convert the current MMAP db files to wiredTiger format]
Start the mongod service using sudo service mongod start command
Restore the database from the backup using [mongorestore][2] command
wiredTiger is being used...

MongoDB installation Ubuntu 12.04 LTS errors

There is actually nothing really wrong here, at least not based on what you have included in the question. Go back to this point:

ubuntu-user@ubuntu-vm:~$ mongo

MongoDB shell version: 3.0.1
connecting to: test
Server has startup warnings: 
2015-03-27T12:37:30.430+0100 I CONTROL  [initandlisten] 
2015-03-27T12:37:30.430+0100 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2015-03-27T12:37:30.430+0100 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2015-03-27T12:37:30.430+0100 I CONTROL  [initandlisten] 
> ^C

At this point you have a running mongod (the procedure you followed installs it as a service), and you have successfully connected to it using the mongo shell, it just has a hugepages warning - that is something you should fix long-term but it does not prevent MongoDB from running.

You then exited the shell and attemped to start another mongod for some reason (you do not need to, the service is still running). If you run mongod without a config file or any options, it will attempt to start with its defaults (port 27017, data directory = /data/db). In this case /data/db does not exist and so you get the error and it terminates.

To fix the error in terms of the hugepages you can alter grub.conf file, as outlined in this answer but you may have made a mistake or omitted something when you made your changes. It's also possible that you will lose those changes if/when you upgrade your kernel. Hence I would recommend undoing your grub changes and trying the second option listed in the answer above, that is, add the command to your /etc/rc.local file.

if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
   echo never > /sys/kernel/mm/transparent_hugepage/enabled
fi
if test -f /sys/kernel/mm/transparent_hugepage/defrag; then
   echo never > /sys/kernel/mm/transparent_hugepage/defrag
fi

As an added bonus, you can run this from the command line (as root), then restart the mongod service to confirm the changes have been picked up successfully.

Best Answer

Related Solutions

MongoDB WiredTiger on Ubuntu – Installation and Configuration

MongoDB installation Ubuntu 12.04 LTS errors

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